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Biology > Cell structure and division > Flashcards

Cell structure and division Flashcards

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1
Q

What are prokaryotic cells?

A

-Single celled organisms
-Smaller and simpler than eukaryotic cells
-Bacteria

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2
Q

What are eukaryotic cells?

A

-Complex
-Include all anima and plant cells as well as algae and fungi

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3
Q

What organelles do animal cells have?

A

-Plasma membrane
-Rough endoplasmic reticulum
-Nucleolus
-Nucleus
-Smooth endoplasmic reticulum
-Lysosome
-Ribosome
-Nuclear envelope
-Golgi apparatus
-Cytoplasm
-Mitochondrion

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4
Q

What organelles do plant cells have?

A

-Have all the same organelles as animal cells and
-Cellulose cell wall
-Vacuole
-Chloroplast

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5
Q

What organelles do algal cells have?

A

-Same organelles as plant cells

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6
Q

What organelles do fungi cells have?

A

-Same organelles as plant cells but with some differences
-Their cell walls are made of chitin not cellulose
-They dont have chloroplast (They don’t photosynthesis)

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7
Q

What is the description and function of the plasma membrane?

A

Description-
-Found on the surface on animal cells and just inside the cell wall of other cells.
-Mainly made of lipids and protein.

Function-
-Regulates the movement of substances into and out of the cell.
-Has receptor molecules on it, allow it to respond to chemicals like hormones.

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8
Q

What is the description and function of the nucleus?

A

Description-
-Large organelle surrounded by a nuclear envelope (double membrane) which contains many pores.
-Nucleus contains chromosomes
-And or more structure called a nucleolus

Function-
-Controls the cell’s activities (by controlling the transcription of DNA)
-DNA contains instructions to make proteins
-The pores allow substances to move between the nucleus and cytoplasm.
-Nucleolus makes ribosomes.

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9
Q

What is the description and function of the mitochondrion?

A

Description-
-Have a double membrane (inner one is folded to form cristae, inside is the matrix which contains enzymes involved in respiration)

Function-
-Site of aerobic respiration where ATP is produced

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9
Q

What is the description and function of the golgi apparatus?

A

Description
-Group of fluid-filled, membrane-bound flattened sacs
-Vesicles are often seen at the edges of the sacks

-Function
-Processes and packages new lipids and proteins
-Makes lysosomes

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9
Q

What is the description and function of the chloroplast?

A

Description-
-Found in plant and algal cells
-Surrounded by double membrane
-Has membranes inside called thylakoid membranes, these membranes are stacked up in some parts of the chloroplast to form grana.
-Grana are linked together by lamellae (thin, flat pieces of thylakoid membrane)

Function-
-Site where photosynthesis takes place
-Some parts of photosynthesis happens in grana and other parts of the photosynthesis happens in the stroma (a thick fluid found in chloroplast)

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10
Q

What is the description and function of the golgi vesicle?

A

Description
-Small fluid-filled sac in the cytoplasm, surrounded by a membrane and produced by the golgi apparatus.

Function-
-Stores lipids and proteins made by the golgi apparatus and transports them out of the cell

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11
Q

What is the description and function of the lysosome?

A

Description-
-Round organelle surrounded by a membrane, with no clear internal structure

Function-
-Contains hydrolytic enzymes (used to digest invading cells or to break down worn out components of the cell)

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12
Q

What is the description and function of the ribosome?

A

Description-
-Either floats free in the cytoplasm or is attached to the rough endoplasmic reticulum
-Made up of proteins and RNA
-Not surrounded by a membrane

Function-
-Site where proteins are made

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13
Q

What is the description and function of the rough endoplasmic reticulum?

A

Description-
-A system of membranes enclosing a fluid-filled space
-surface is covered with ribosomes

Function-
-Folds and processes proteins that have been made by ribosomes

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14
Q

What is the description and function of the smooth endoplasmic reticulum?

A

Description-
-Similar to rough endoplasmic reticulum but with no ribosomes

Function-
-Synthesis and processes lipids

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15
Q

What is the description and function of the cell wall?

A

Description-
-Rigid structure that surrounds cells in plants, algae and fungi.
-In plants and algae its made mainly of the carbohydrate cellulose
-in fungi its made of chitin

Function-
-Supports cells and prevent them from changing shape

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16
Q

What is the description and function of the cell vacuole?

A

Description-
-Membrane-bound organelle found in the cytoplasm of the plant cells.
-Contains cell sap (weak solution of sugar and salts.
-The surrounding membrane is called the tonoplast.

Function-
-Helps to maintain pressure inside the cell and keep the cell rigid.
-Stops plants wilting.
-involved in the isolation of unwanted chemicals inside the cell

17
Q

What can specialised cells form?

A

-Specialised cells are grouped together to form tissues (group of cells working together to perform a particular function)
-Different tissues work together to form organs
-Different organs make up an organ system

18
Q

From production to secretion, list in order, four organelles involved in making hormones.

A

Ribosome- Rough endoplasmic reticulum- Golgi apparatus- Golgi vesicle

19
Q

What organelles does a bacteria contain?

A

-Doesnt have a nucleus, DNA floats free in the cytoplasm
-Circular DNA present as one long coiled up strand
-Cytoplasm
-Plasma membrane
-Cell wall (made of a polymer called murein)
-Flagellum
-Plasmids
-Capsule (made up of secreted slime, helps to protect bacteria from attack)

20
Q

What is flagellum?

A

-Found in bacteria
-Long, hair like structure that rotates to make the prokaryotic cell move.
-Not all prokaryotes have a flagellum,

21
Q

What is plasmid- bacteria?

A

-Small loops of DNA that arent part of the main circular DNA molecule
-Contain genes for antibiotic resistance (can be passed between prokaryotes)

22
Q

What is the structure of a virus?

A

-Nucleic acids surrounded by protein coat called the capsid
-Smaller than bacteria
-Unlike bacteria, no plasma membrane, no cytoplasm and no ribosome
-Invade and reproduce inside the vells of other organisms
-Contain a core of genetic material either DNA or RNA
-Attachment proteins on the capsid

23
Q

Explain binary fission?

A

-The cell replicates its genetic material before physically splitting into two daughter cells.
1)The circular DNA and plasmids replicate. The main DNA loop replicated once but plasmids can be replicated loads of times.
2)The cell gets bigger and the DNA loops move to opposite poles of the cell
3)The cytoplasm begins to divide and new cell wall begins to form
4)The cytoplasm divides and two daughter cells are produced. Each daughter cell has one copy of the circular DNA, but can have a variable number of copies of the plasmids.

24
Q

How does viruses replicate themselves?

A

-Use host cells
-Use their attachment proteins to bind to complementary receptor proteins on the surface of host cells.
-Different viruses have different attachment proteins and therefore require different receptor proteins on host cells
-Because they’re not alive, viruses don’t undergo cell division. Instead they inject DNA or RNA into the host cell to replicate the viral particles

25
Q

Formula of magnification=

A

Magnification= size of the image/ size of the real object

26
Q

Optical (light) microscope vs Electron microscopes-

A

-Optical microscope use light to form an image whereas electron microscope use electrons to form an image.
-Electron microscope has a higher resolution (0.0002) than optical microscope(0.2 micro meters)
-maximum useful magnification of an optical microscope is about x1500 whereas maximum useful magnification of an electron microscope is about x1500000

27
Q

What are the two types of electron microscope? Describe them-

A

1)Transmission electron microscopes (TEMs)
-Use electromagnets to focus a beam of electrons, which is then transmitted through the specimen.
-Denser parts of the specimen absorb more electrons, makes them look darker on the image.
-Give high resolution images, can see the internal structure of organelles
-Can only be used on thin specimens

2)Scanning Electron microscopes (SEM’s)
-Scan a beam of electrons across the specimen. Knocks off electrons from the specimen, which are then gathered in a cathode ray tube to form an image.
-Images show the surface of the specimen and can be 3D
-Can be used on thick specimens
-Lower resolution than TEMs

28
Q

What are the 3 steps of the cell fractionation?

A

1)Homogenisation- breaking up the cells
2)Filtration- Getting rid of the big bits
3)Ultracentrifugation- Separating the organelles

29
Q

Describe the first step of the cell fractionation-

A

-Homogenisation
-Can be done by grinding the cells up in a blender.
-This breaks up the plasma membrane and releases the organelles into solution.
-Solution must be kept ice-cold to reduce the activity of enzymes that break down organelles.
-Solution should be isotonic, means it should have the same conc of chemicals as the cells being broken down, to prevent damage to the organelles through osmosis.
-A buffer solution should be added to maintain the pH

30
Q

Describe the second step of the cell fractionation-

A

-Filtration
-Cell solution is filtered through a gauze to separate any tissue debris from the organelles.
-The organelles are much smaller than the debris so they pass through it.

31
Q

Describe the third step of the cell fractionation-

A

-Ultracentrifugation
-First, the cell fragments are poured into a tube, the tube is put into a centrifuge and is spun at a low speed. The heaviest organelles = get flung to the bottom of the tube by the centrifuge to form a thick sediment at the bottom called the pellet. Rest of the organelles stay suspended in the fluid above the sediment- the supernatant
-Supernatant is drained off and poured into another tube and spin at a higher speed
-this process is repeated until the organelles are separated.

32
Q

What happens in mitosis?

A

-A parent cell divides to produce two genetically identical daughter cells
-Needed for the growth of multicellular organisms and for repairing damaged tissues

32
Q

What are the stages of mitosis-

A

-Interphase
-Prophase
-Metaphase
-Anaphase
-Telophase

33
Q

Describe the each stage of mitosis?

A

1)Interphase-
-The cells DNA is unravelled and replicated to double its genetic content.
-The organelles are also replicated so it has spare ones and its ATP content is increased

2)Prophase-
-The chromosomes condense, getting shorter and fatter.
-Centrioles (tiny bundles of proteins) start moving to opposite ends of the cells, forming a network of protein fibres across, called spindle
-The nuclear envelope breaks down and chromosomes lie free in the cytoplasm

3)Metaphase-
-Chromosomes line up along the middle of the cell and become attached to the spindle by their centromere

4)Anaphase-
-Centromeres divide, separating each pair of sister chromatids.
-Spindles contract, pulling chromatids to opposite poles of the spindle
-This makes the chromatids appear V shaped
-Division of the cytoplasm starts

5)Telophase-
-Chromatids reach the opposite poles on the spindle
-They uncoil and become long and thin again. (Now called chromosomes)
-A nuclear envelope forms around each group of chromosomes, so there are now two nuclei.
-Division of the cytoplasm finishes in telophase
-There are now two daughter cells that are genetically identical to the original cell and to each other.

34
Q

What are the two cancer treatments that target the cell cycle?

A

Treatments for cancer are designed to control the rate of cell division in tumour cells by disrupting the cell cycle. Treatments don’t distinguish tumour cells from normal cells- also kill normal body cells. However tumour cells divide more frequently than normal cells so the treatment is more likely to kill tumour cells.

1)G1 (Cell growth and protein production) Some chemical drugs (chemotherapy) prevent the synthesis of enzymes needed for DNA replication. If these arent produced, the cell is unable to enter the synthesis phase, disrupting the cell cycle and forcing the cell to kill itself.

2)S phase (DNA replication)- Radiation and some drugs damage DNA, At several points in the cell cycle the DNA in the cell is checked for damage. If severe damage is detected, the cell will kill itself- preventing further growth.

35
Q

What is the formula for mitotic index?

A

Number of cells with visible chromosomes/Total number of cells observed

36
Q

Cell division- investigating mitosis practical-Root tips can be stained and squashed to observe mitosis- Method

A

-Cut 1 cm from the a growing root. It needs to be the tip because thats where the growth occurs (where mitosis takes place)
-Prepare a boiling tube containing 1M hydrochloric acid and put it in a water bath at 60 Celsius degrees
-Transfer the root tip into the boiling tube and incubate for about 5 minutes
-Rinse the root tip well with cold water. Leave the trip to dry on a paper towel
-Place the root tip on a microscope slide and cut 2 mm from the very tip of it. Get rid of the rest.
-Use a mounted needle to break the tip open and spread the cells out thinly.
-Add a few drops of stain and leave it for a few minutes. The stain will make the chromosomes easier to see under a microscope.
-Place a cover slip over the cells and push down firmly to squash the tissue, This will make the tissue thinner and allow light to pass through it. Dont smear the cover slip sideways
-Now you can see all the stages of mitosis under an optical microscope

37
Q

How to set up and use an optical microscope?

A

-Start by clipping the slide you’ve prepared onto the stage
-Select the lowest powered objective lens
-Use the coarse adjustment knob to bring the stage up to just below the objective lens
-Look down the eyepiece, use the coarse adjustment knob to move the stage downwards, away from the objective lens until the image is roughly in focus
-Adjust the focus with the fine adjustment knob, until you get a clear image of whats on the slide.
-If you need to see with a greater magnification, swap to a higher powered objective lens and refocus

38
Q

How to calculate the actual size of the cell?

A

Actual size= Size of image/magnification

39
Q

How to distinguish between dividing cells and non dividing cells?

A

-If a cell contains visible chromosomes, this means it’s dividing

40
Q

Penicillin is an antibiotic that can be used to treat infections of staphylococcus aureus. The drugs cause cell lysis, by inhibiting cell wall synthesis. Explain why these drugs have no effect on human cells?

A

-Human cells have no cell wall so the drugs won’t have any effect on them.

41
Q

DNA is related to the function of the sperm cell and a mitotic cell.
A mitotic cell has many ribosomes, but a sperm cell does not.
With reference to the functions of these cells, explain why there is this difference in organelles.

A

-The function of the sperm cell is to deliver the genetic material to the egg cell, it isn’t necessary for it to make lots of proteins for cell growth and repair.
-A mitotic body cell is undergoing mitosis
-So it requires ribosomes for cell growth prior to division

Biology (12 decks)

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